The disclosures herein relate in general to electronic circuitry, and in particular to reducing a settling time after a slew condition in an amplifier.
An amplifier's slew rate is a measure of a maximum rate of change of the amplifier's output voltage in response to an input step function of the amplifier's input voltage. For example, the amplifier's input voltage may be a differential input voltage. A high slew rate is generally desirable.
The amplifier may include a slew boost circuit for: (a) detecting a condition (“slew condition”) in which a threshold difference arises in the differential input voltage; and (b) in response to the slew condition, generating slew current for maintaining the high slew rate. After the slew condition ends (e.g., slew current=0), the amplifier settles various currents and voltages over a period of time (“settling time”) to their usual operating levels. However, in a conventional 3-stage amplifier with the slew boost circuit, the settling time may be unsuitable (e.g., 16-18 bit) for some applications, such as an analog-to-digital converter (“ADC”) driver with high speed and high resolution.